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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Dell WMI descriptor driver4 *5 * Copyright (C) 2017 Dell Inc. All Rights Reserved.6 */7 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt9 10#include <linux/acpi.h>11#include <linux/list.h>12#include <linux/module.h>13#include <linux/wmi.h>14#include "dell-wmi-descriptor.h"15 16#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"17 18struct descriptor_priv {19 struct list_head list;20 u32 interface_version;21 u32 size;22 u32 hotfix;23};24static int descriptor_valid = -EPROBE_DEFER;25static LIST_HEAD(wmi_list);26static DEFINE_MUTEX(list_mutex);27 28int dell_wmi_get_descriptor_valid(void)29{30 if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID))31 return -ENODEV;32 33 return descriptor_valid;34}35EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid);36 37bool dell_wmi_get_interface_version(u32 *version)38{39 struct descriptor_priv *priv;40 bool ret = false;41 42 mutex_lock(&list_mutex);43 priv = list_first_entry_or_null(&wmi_list,44 struct descriptor_priv,45 list);46 if (priv) {47 *version = priv->interface_version;48 ret = true;49 }50 mutex_unlock(&list_mutex);51 return ret;52}53EXPORT_SYMBOL_GPL(dell_wmi_get_interface_version);54 55bool dell_wmi_get_size(u32 *size)56{57 struct descriptor_priv *priv;58 bool ret = false;59 60 mutex_lock(&list_mutex);61 priv = list_first_entry_or_null(&wmi_list,62 struct descriptor_priv,63 list);64 if (priv) {65 *size = priv->size;66 ret = true;67 }68 mutex_unlock(&list_mutex);69 return ret;70}71EXPORT_SYMBOL_GPL(dell_wmi_get_size);72 73bool dell_wmi_get_hotfix(u32 *hotfix)74{75 struct descriptor_priv *priv;76 bool ret = false;77 78 mutex_lock(&list_mutex);79 priv = list_first_entry_or_null(&wmi_list,80 struct descriptor_priv,81 list);82 if (priv) {83 *hotfix = priv->hotfix;84 ret = true;85 }86 mutex_unlock(&list_mutex);87 return ret;88}89EXPORT_SYMBOL_GPL(dell_wmi_get_hotfix);90 91/*92 * Descriptor buffer is 128 byte long and contains:93 *94 * Name Offset Length Value95 * Vendor Signature 0 4 "DELL"96 * Object Signature 4 4 " WMI"97 * WMI Interface Version 8 4 <version>98 * WMI buffer length 12 4 <length>99 * WMI hotfix number 16 4 <hotfix>100 */101static int dell_wmi_descriptor_probe(struct wmi_device *wdev,102 const void *context)103{104 union acpi_object *obj = NULL;105 struct descriptor_priv *priv;106 u32 *buffer;107 int ret;108 109 obj = wmidev_block_query(wdev, 0);110 if (!obj) {111 dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");112 ret = -EIO;113 goto out;114 }115 116 if (obj->type != ACPI_TYPE_BUFFER) {117 dev_err(&wdev->dev, "Dell descriptor has wrong type\n");118 ret = -EINVAL;119 descriptor_valid = ret;120 goto out;121 }122 123 /* Although it's not technically a failure, this would lead to124 * unexpected behavior125 */126 if (obj->buffer.length != 128) {127 dev_err(&wdev->dev,128 "Dell descriptor buffer has unexpected length (%d)\n",129 obj->buffer.length);130 ret = -EINVAL;131 descriptor_valid = ret;132 goto out;133 }134 135 buffer = (u32 *)obj->buffer.pointer;136 137 if (strncmp(obj->string.pointer, "DELL WMI", 8) != 0) {138 dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",139 buffer);140 ret = -EINVAL;141 descriptor_valid = ret;142 goto out;143 }144 descriptor_valid = 0;145 146 if (buffer[2] != 0 && buffer[2] != 1)147 dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",148 (unsigned long) buffer[2]);149 150 priv = devm_kzalloc(&wdev->dev, sizeof(struct descriptor_priv),151 GFP_KERNEL);152 153 if (!priv) {154 ret = -ENOMEM;155 goto out;156 }157 158 priv->interface_version = buffer[2];159 priv->size = buffer[3];160 priv->hotfix = buffer[4];161 ret = 0;162 dev_set_drvdata(&wdev->dev, priv);163 mutex_lock(&list_mutex);164 list_add_tail(&priv->list, &wmi_list);165 mutex_unlock(&list_mutex);166 167 dev_dbg(&wdev->dev, "Detected Dell WMI interface version %lu, buffer size %lu, hotfix %lu\n",168 (unsigned long) priv->interface_version,169 (unsigned long) priv->size,170 (unsigned long) priv->hotfix);171 172out:173 kfree(obj);174 return ret;175}176 177static void dell_wmi_descriptor_remove(struct wmi_device *wdev)178{179 struct descriptor_priv *priv = dev_get_drvdata(&wdev->dev);180 181 mutex_lock(&list_mutex);182 list_del(&priv->list);183 mutex_unlock(&list_mutex);184}185 186static const struct wmi_device_id dell_wmi_descriptor_id_table[] = {187 { .guid_string = DELL_WMI_DESCRIPTOR_GUID },188 { },189};190 191static struct wmi_driver dell_wmi_descriptor_driver = {192 .driver = {193 .name = "dell-wmi-descriptor",194 },195 .probe = dell_wmi_descriptor_probe,196 .remove = dell_wmi_descriptor_remove,197 .id_table = dell_wmi_descriptor_id_table,198};199 200module_wmi_driver(dell_wmi_descriptor_driver);201 202MODULE_DEVICE_TABLE(wmi, dell_wmi_descriptor_id_table);203MODULE_AUTHOR("Mario Limonciello <mario.limonciello@outlook.com>");204MODULE_DESCRIPTION("Dell WMI descriptor driver");205MODULE_LICENSE("GPL");206